"I was freaking out," Siau said. "I had to calm down and think about how he could have possibly gotten out. And it came to me that was the only time that I could have got out and I wouldn't have seen him. I was just sure he was there."

But the Arkansas-based truck driver feared he'd lose his job if he turned around. He called authorities, eventually reaching a local animal control officer who went to the site on Sunday.

"Sure enough," the Associated Press reported, "little Rambo was there, sitting patiently." He was taken to an animal shelter in Hannibal until Siau could collect him.

According to the animal control officer, Tim Ledbetter, a family that had stopped at the rest area had offered to adopt Rambo. "In about 60 seconds, he would have been gone," Ledbetter said.

Siau returned Tuesday to pick up Rambo, who "began to whimper, tremble and squirm" when he heard his owner call his name.